


Candy is Dandy?

by Largishcat



Category: Invader Zim
Genre: Aged-Up Character(s), Alien Biology, Canon-Typical Violence, Dib Gets Himself in Over His Head Again, First Time, Gift Work, M/M, Mating Cycles/In Heat, Xenophilia
Language: English
Status: Completed
Published: 2019-10-15
Updated: 2019-10-15
Packaged: 2020-11-01 06:47:38
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 5,988
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20810822
Author URL: https://archiveofourown.org/users/Largishcat/pseuds/Largishcat
Summary: “Listen here,slime pig, Zim is no more happy about this than you. But,” he waved a hand imperiously, “since you insist, Zim supposes he will accept your help. Loathsome as it is.”“But I didn’t offer you any help,” Dib said.





	Candy is Dandy?

**Author's Note:**

> Written for a lovely person with very good taste.

Dib came back from summer vacation with a deep tan, two hundred new followers on his conspiracy blog, and a new determination that senior year was going to be the year he exposed Zim to the world. 

Someone out there had to have it in for Dib, though. Because things went wrong immediately. Dib took his seat in first period AP Physics and Zim sneered at him from across the room and his heart… didn’t flutter exactly, but beat a little wrong.

That was normal and _fine_, though—that had been happening since freshman year when Zim had tackled him behind the football field and he’d first realized how much _smaller_ Zim now seemed. He could wrap his entire hand around one of Zim’s skinny thighs. Then Zim had tried to skewer him with one of his PAK legs and Dib’s attention was dragged back to the fight, but somehow that new awareness lingered. The awareness of Zim not just an abstract concept of interstellar evil, but as a being with a physical form. 

And that had been _fine_. It was just something new and weird that came with being a teenager. It didn’t change anything. Dib did his homework, he chased vampires and Jersey Devils and jackalopes, he fought Zim. If sometimes he zoned out staring at the weird way the light played over Zim’s weird skin, then that was _fine_ too. 

Dib comforted himself with that thought. Told himself this was going to be just another normal school year, and at the end of it Zim would be in a specimen jar and Dib would be trying to find time to read his college acceptance letters in between giving television interviews.

It wasn’t just another normal school year. Something had changed over the summer. Maybe it was because he hadn’t seen the little green bastard for a couple months, but suddenly he wasn’t noticing Zim’s skin every once in a while, he was noticing it _all the time_. And his delicate, sharp, little three-fingered hands, his jointed, worm-like tongue, the stupid way he marched everywhere like he was on parade. The way his voice grated in the depths of Dib’s ears and the back of his teeth, and the easy agility with which he ran and jumped and fought. 

Dib _suffered_ through this horrible hyperawareness for months. Suffered like no teenager had ever suffered.

He wished sometimes that he had someone to talk to, but he couldn’t talk to his family and risk his dad trying to invite Zim to dinner again—last time had been a _disaster_—and when he’d tried to bring it up with the Eyeballs they’d all either hurriedly changed the subject or started telling him _very_ disturbing stories. He still broke out in a cold sweat remembering Agent Tunaghost’s “encounter” with a goat-man in Kentucky.

But the lives of paranormal investigators and truth-seekers were solitary ones, and it wasn’t like Dib wasn’t used to solving problems on his own.

Currently, he was problem solving by subtly inching his lab stool to the left until he had a perfect view of Zim’s workstation, the clock above the door, and the side of the Chemistry teacher’s head all at once. 

It was fifteen minutes until the end of the day and Zim had been acting off since that morning. There wasn’t the usual crispness in his step, and he had barely even screamed when the lunch lady had offered him a cheeseburger. 

He’d been fidgeting too. Tapping his fingers on his thighs and shifting his weight constantly like his pants were too tight.

Now, Zim was watching his filtration drip with glazed eyes. There was a strange sheen on his skin, like the shimmer on a gas slick. 

He had a table by himself, since his lab partners had a tendency to end up in the nurse’s office with chemical burns and the other kids had finally noticed a pattern.

As Dib watched, Zim began to rock back and forth on his stool. It was subtle enough that someone who wasn’t staring intently at Zim might not notice, but Dib _was_ staring intently and he _did_ notice. He leaned sideways on his own stool, almost tipping over as he tried to get a better look. Dib’s lab partner sighed pointedly, but Dib ignored them.

Zim’s face was only visible in three-quarters profile from this angle, but Dib still caught it when Zim bit his lip. He crossed his legs, booted feet dangling a foot off the floor, and gripped the metal lip of the lab table tight enough that Dib could hear the material of his gloves creak. Dib knew those gloves were reinforced with something like kevlar—Zim had to be exerting a lot of pressure to make them groan like that.

Zim’s mouth sagged open on an exhale, his tongue peeking out from between his teeth. 

Zim sat up straight at the same time as Dib became aware of a cloying hot-sweet-sour candy smell in the air, like melting sour patch kids. 

Under his incredulous gaze, Zim reached out, grabbed his half-done filtration, and dumped it over his own head.

“Teacher drone!” Zim shouted as the sludgy mixture of salicylic acid and charcoal ran down his face. “I have become contaminated and must go to the restroom to cleanse myself immediately!”

“Oh, you should use the chemical shower, Zim—” the teacher began to say, but Zim was already out the door, that strange sour-sweet smell trailing after him.

Dib’s hand shot up.

“Just go,” the teacher sighed. “Grab a copy of the worksheet on your way out.”

Dib slammed into the hallway in time to see Zim sprinting towards the boys bathroom, dodging around the scattered students milling around the lockers. Dib started after him, choosing to go through people rather than around them. They could dodge, he had a world to save.

“Dib, you _suck!_” Zeeta yelled as he shoved her out of his way, nearly knocking her into her open locker, but he barely noticed, eyes fixed on Zim’s retreating back. 

His mind raced. He’d been watching Zim’s workstation like a hawk all period, but that smell—had Zim managed to mix something up without him noticing? 

Wasn’t nitroglycerine supposed to smell like candy?

Ahead of him, Zim disappeared into the boy’s bathroom. Seconds later there was a crash and chorus of screams. Two sophomore boys ran out of the door just as Dib was skidding to a stop in front of it.

He hesitated before pushing the door open, prepared for anything. Zim brandishing some kind of superweapon, the bathroom on fire, a swarm of flying space leeches like last Tuesday—

There was none of that when Dib slipped inside. The room was empty except for a backpack abandoned by one of the urinals. And Zim. 

Zim stood in front of one of the sinks, clutching the edges in a grip so tight his arms were trembling. Actually, his whole body seemed to be trembling. He was staring down his own reflection like he wanted it to blink first.

“Zim?” Dib said. He meant it to come out as an accusation, but he ended up sounding hesitant, unsure.

Zim whipped around, one hand reaching back towards his PAK like he was going to pull out a weapon. Dib took a step back, wary.

“_Dib_,” Zim hissed. “What do you want?”

“I, um.” Zim looked _awful_ now that Dib saw his face. His skin looked slick and yellowish under the bathroom’s fluorescent lights. There were splotches of deep green under his eyes like he hadn’t slept, and he was swaying on his feet. “What’s wrong with you?”

Zim sneered at him, except his lip curled back too far from his teeth, turning the expression into a snarl. Dib resisted the urge to take another step back. “Zim’s business is none of yours, human,” Zim said. “I have no time for your child games today.” 

He turned back to the mirror, obviously dismissing Dib, but Dib hadn’t gotten this far in life by doing what Zim wanted. He took a cautious step forward, then another when Zim didn’t react. 

The smell grew in intensity as he got closer. It itched in the back of his nostrils. 

There was some kind of liquid splashed on the bottom of the mirror. It dripped down the sides of the sink, pooling on the floor.

He was right behind Zim now. He saw himself looming in the mirror, impossibly tall and dark behind Zim’s tiny, colorful form. But Zim didn’t seem to notice, staring at his own reflection like he was hypnotized.

Okay, Dib would have to move fast to make this work.

He grabbed Zim by the shoulder, yanking him so he spun around. Then, before Zim could do more than blink, Dib lifted him and slammed him back so his body was folded almost in half, his PAK wedged in the sink. If he tried to extend his legs now, they would have to punch through the porcelain first. It wasn’t much, but it would buy Dib a couple of seconds.

This close, the candy smell made Dib want to sneeze. “What are you up to this time, _Zim?_” he demanded, stepping in between Zim’s legs so he wouldn’t be able to knee Dib in the crotch. _That_ was a lesson Dib learned the hard way.

He expected Zim to immediately start yelling and struggling, but he didn’t. He made a high, clicking sound in the back of his throat and arched up against Dib. It was about now that Dib realized that liquid that was all over the sink was also completely soaking the front of Zim’s uniform, and it was _gooey_. Great.

“Hey, seriously, what’s going on?” Dib said, shaking Zim, making his whole body flop back and forth. It was always weird re-realizing how little Zim weighed. His personality was so big it seemed to have its own gravitational field, but his tiny body weighed _nothing_. “Zim? Is this like the brain worm thing again—_hey—_” Zim wrapped his legs lightning fast around Dib’s hips, but didn’t move in for an attack. He just pressed himself closer. Pulled Dib in until they were so close Dib could feel the steady hum of Zim’s PAK pumping blood through his body.

Dib felt himself start to get hard, which absolutely could _not_ happen right now.

He risked loosening his grip on Zim long enough to slap him across the face. _That_ snapped Zim out of whatever weird trance he was in. His eyes snapped up to Dib’s, aware and brimming with rage.

“Unhand me, Dib-thing,” Zim said quietly, a note of real danger in his voice. But Dib had been shot, stabbed, blown up, and hurled into space by Zim too many times be intimidated by him now. 

“Nuh-uh, Zim,” he said, pushing Zim down harder into the sink. The metal of his PAK made a screeching sound against the ceramic. “Tell me what you’re doing. What’s that smell? What’s this oozy stuff? Some kind of chemical weapon? Alien molting? Are you experimenting with cologne—”

Zim writhed like a snake and it was all Dib could do to keep him pinned. “I said I don’t have _time_ for you, you dirty pig animal!” Zim shouted. “Let me go! I’m busy!”

Dib lifted Zim up only to slam him back down. Zim’s head bounced off the edge of the mirror with a loud crack. He made a low noise deep in his throat, his eyes going unfocused again. 

Dib wondered if he’d managed to give Zim a concussion or something, but all thoughts flew out of his head as Zim _ground his hips_ against Dib’s _crotch_, making that same sound like a malfunctioning bug-zapper. That’s when things finally clicked.

“Oh, my God.” Dib stepped back, one hand on Zim’s chest to keep him pinned, but keeping him at arm’s length. “_Oh,_ my God, is that _sex_ goo? Is this an alien _sex_ thing?”

He considered letting Zim go, but didn’t get the chance because that was when Zim drove the heel of his boot into Dib’s nose. Pain exploded across his face and he thought he heard something snap. He stumbled back, dropping Zim as he raised his hands to clutch at his nose. 

He felt a rush of displaced air as Zim ran past him, and turned around just in time to see Zim slam open the bathroom door with one of his PAK legs and disappear down the hall.

Dib caught a glimpse of himself in the mirrors as he rushed after Zim. There was blood dripping from his left nostril and his whole front was soaked in that goo. He looked flushed and wild-eyed. 

The hall was full of students—the final bell must have rung while they were in the bathroom—and Zim was already three rows of lockers ahead, _openly_ sprinting on his PAK legs in a building full of humans.

“How are _none_ of you noticing this!?” Dib yelled as he ran down the hall after Zim’s rapidly retreating form. He had to shove and dodge around the milling crowd to get through. Zim avoided the press of bodies by leaping up to the ceiling on his PAK legs and scuttling down the hallway upside down like a horrible little spider. No one glanced up, even when a dislodged ceiling tile fell directly onto Greta’s head. _“Are you fucking serious?_” Dib howled as Zim slipped through the front doors and out of sight.

“Language, young man!” said a voice directly behind Dib, almost making him trip. He turned around to see the Vice Principal with murder in her eyes.

Twenty minutes of getting yelled at later and Zim was long gone. Luckily, there was really only one place he would go.

The route to Zim’s base was long-memorized and Dib jogged it on autopilot. He didn’t actually know what he planned on doing once he got there, only that he had to put a stop to Zim’s… whatever it was. His thoughts bounced back and forth between horrifying images of Zim hatching an army of mini-Zims and the way it had felt to have Zim pinned under him. Have him pull Dib in closer, crooning, moving, _wanting_—

He still didn’t have a plan as he slowed to a walk in front of Zim’s house. 

Every house on the block had gotten a new coat of paint over the years, or new flower bushes, or a gazebo, but not Zim’s. His house looked the same as the day it had first appeared. Small, green, unchanging even as the world changed around it.

The security system had also never been upgraded, which meant it was no time at all until Dib was inside, bent almost double, creeping through the corridors of Zim’s inner base. 

It was eerily quiet. He was used to the halls down here echoing with Zim or GIR’s yelling, or the sound of machinery, or explosions, or the zing-pop of lasers flying over his head. But GIR was nowhere to be seen and wherever Zim was lurking, he was quiet.

Dib was on the verge of banging on pipes and yelling in an attempt to draw Zim out when he noticed lights flickering behind a half-open door. He slowed his steps, feeling with the instinct of long experience that Zim was just around the corner. 

He pressed the door open a little further, peering inside.

The first thing he saw was Zim’s bare shoulders, dusty green and almost grotesquely thin. He was stripped to the waist, disguise off and PAK plugged into a bank of monitors. The light from the computer monitors played over Zim’s face and reflected in his half-lidded eyes, but Zim paid the scrolling text on them no mind. Instead he was rocking back and forth on his chair with his hand down the front of his leggings. His other hand, gloveless, gripped on the edge of the counter. 

Somehow, that was the detail that caught Dib. The sight of Zim’s strange, three-fingered little hand flexing on the counter as Zim’s mouth fell open on a gasp and he hunched over on himself. Dib felt the stirrings of arousal bubble up in his stomach like hot magma.

He stood frozen with his nose poking around the corner. What on earth were you _supposed_ to do when you walking in on your worst enemy masturbating? Cough loudly? Barge in?

The sticky-sour scent of Zim’s arousal was thick in the air, and standing stock still, barely breathing, Dib could hear the slick sounds of Zim touching himself.

Dib’s hands were pushing the door open and his feet were taking him inside before his brain was aware of what he was doing.

Zim’s eyes rose to look at him, but they were dull, unfocused like Zim didn’t really see him. His antennae didn’t even perk up. Zim didn’t pull his hand out of his leggings either.

“Dib?” Zim said, sounding confused. “What are you doing here?”

“I’m—we were fighting, remember?” Dib pointed to his face where the blood was still crusted underneath his nose. “You kicked me, I chased you?”

“Yes… of course.” Zim finally pulled his hand out of his pants to rub at both of his eyes. Dib saw he was coated to the wrist in slime. It left a thick smear across his cheek. Dib had the strong impulse to reach out and coat his fingers with it. Rub them together and see what it felt like, what it tasted like.

Shaking himself, Dib took another step forward. This time, Zim’s antennae shot up, his eyes actually focusing.

“Dib!” he said. “What are _you_ doing here, filth-monster?”

“We _literally_ just went over this,” Dib said. “Except you didn’t insult me last time. Now, you’re _going_ to tell me what the fuck is going on with you right now.”

“_Eh?_ I am?”

“Yes! Explain.” Honestly, this was good. If anything was going to kill his awkward boner, it was Zim’s personality.

“Okay,” Zim said. He blinked slowly, like he was trying to gather his thoughts. “Zim is in squeedge?”

Dib frowned. “Explain more.”

“It’s really too complex for your inferior human brain to grasp,” Zim said, pulling down a screen and swiping at it until it was displaying a completely incomprehensible diagram of what might have been a deconstructed PAK. Or a cross-section of a sprouting potato.

Dib watched Zim’s clawed fingertips dance on the screen and reflected on how absolutely, profoundly fucking _weird_ it was to be standing here listening to Zim rant when not even an hour ago Zim had been clawing him closer like he was trying to crawl inside Dib’s skin.

“… Is malfunctioning,” Zim was saying, the display on the screen shifting along with his words. “Without the squeedgy-suppressor functioning all the squeedge juice is free to run through my insides, causing,” he paused dramatically, “_things_. Horrible things.”

Dib blinked at a diagram of what sure looked like eggs being fertilized. It had a little cartoon of a frowning irken face with X’s for eyes next to it. Eggs bad?

“Sex things,” Dib said. It wasn’t really a question. His eyes kept drifting to where Zim was clenching and unclenching one of his hands in the cloth of his leggings.

Zim gave an exaggerated shudder and Dib felt a hysterical giggle climbing up his throat. “You’re just fucking horny, Zim, holy _shit_.” Zim glared at him and his giggle evolved into a full-blown laugh. He bent over, bracing himself on his knees. “Jeez, Zim, can’t you just, I don’t know, jerk off? Take the edge off?”

“No,” Zim said, and his tone was so flat and cold that Dib looked up. “There is a reason my people don’t _breed_ like filthy animals anymore. If my body’s horrible _urges_ are not satisfied, it will start to shut down.”

“Oh.” If Dib were smart, he’d turn on his heel and go straight home and assume Zim would turn up at school in a week or two good as new and yelling about something. He always did. This wasn’t the weirdest kind of trouble Zim had gotten himself into over the years. Except for all the ways that it really _was_. 

The thought occurred to him that if Zim was dying, he should let him. Swoop in and collect the corpse afterwards. Take GIR, take what he could from the base. Publish some research. Patent the specs to the Voot Cruiser and get rich off them. That would also be a smart thing to do. Instead, he just stood there like an idiot, trying to think of something to say.

Zim snorted and spun in his chair. He pulled another couple of screens down towards him with hands that Dib could see were trembling. “Begone, Dib-stink,” he said, “these matters are beyond your _monetary classification_.”

“... You mean above my pay grade? Wait, no, that’s _stupid_. This is all _stupid_. Isn’t there—”

“Listen here, _slime pig_,” Zim said, spinning back around, “Zim is no more happy about this than you. But,” he waved a hand imperiously, “since you insist, Zim supposes he will accept your help. Loathsome as it is.”

“But I didn’t offer you any help,” Dib said.

Zim ignored him, typing something on his computer that made all the wires attached to his PAK retract at once. He hopped down to the floor. Dib watched in uncomprehending alarm as Zim began to struggle out of his boots.

“Uh, what are you doing?”

“You can’t breed me if I have my pants on.” Zim hooked his thumbs in the waistband of his leggings, giving Dib a look of pure contempt. “Honestly, human, keep up.”

Dib had the bizarre experience of feeling outrage, alarm, and helpless arousal all at once. “I can’t fucking _what?_”

“Breed me, are you deaf? If I can fool my terrible squeedgy bits into thinking I’ve collected enough goosh to fertilize a brood of eggs, then I’ll be free to fix the suppressor and continue conquering this terrible planet! You produce goosh. Zim has watched you.”

“That’s—_what do you mean you’ve watched me?_” 

“At night! Zim is always watching!”

“Oh, my God.” Dib put his hands over his face. Maybe he should go stand in the middle of Zim’s yard and let the gnomes shoot him. That would be less painful than this conversation.

“You smell like meat, human.”

“What?” Dib’s eyes jerked back to Zim’s face to see him focused intently on him. Eyes bright and feverish. “_Excuse_ me?”

“You creatures,” Zim flicked two of his clawed fingers, like Dib’s whole species was a bothersome fly he wanted to brush away, “you keep too much metal in your _disgusting_ blood. You always stink of it _oxidizing_. Your species is nothing but rust and _dookie_.” Dib didn’t know how to respond to that, but Zim didn’t give him the chance. He held out one of his hands, so strange and small without his gloves, palm up. “Come closer, Dib-meat.”

“Why?” Dib asked suspiciously.

“_Do not question Zim!_” Zim shrieked, then quieted, frowning to himself. “Your horrible skin looks very soft.”

“You can’t have it.”

“Shut up! I don’t want it!” Zim flexed his outstretched hand, claws glinting in the low light. “Come here. Stop wasting Zim’s time.”

Dib took a step forward, then another. Zim might have thought he stunk, but it was Zim’s smell that filled the air down here. Sugary, chemical, intoxicating; Dib licked his lips and tasted it on his tongue. 

He reached out to place his palm lightly on top of Zim’s, dwarfing Zim’s hand. When had his fingers gotten so long? When did Zim start to seem so small—_when_ had Zim taken his pants off? 

Dib kept his eyes on Zim’s face, despite intense curiosity he wasn’t quite ready to deal with whatever was down there. Instead he reached out and did something he had wanted to do for years. He put his palm in the center of Zim’s bare chest and held it there, just feeling the cool, leathery feel of Zim’s skin, and the little grumbles and pulses of his squeedilyspooch working. It didn’t beat like a heart, it was more of a steady, almost mechanical thrum. 

Dib’s hand covered almost the entirety of Zim’s chest. The tips of his fingers just resting on Zim’s collarbones, his thumb curling around Zim’s rib cage.

Zim blinked up a him, antennae held at a curious half-mast. His hands came up, curling around Dib’s wrist, his claws prickling Dib’s skin. “Zim will show you what to do,” he said, voice low and quiet.

Dib felt arousal in the back of his nose, like the burn of wasabi. Or maybe it was the scent of Zim heavy in the air, making Dib dizzy and shaky and _present_ in his own skin in a way he wasn’t used to. It had to be pheromones, because Dib had been turned on before—obviously, he was a _teenager_—but not like this. No one had ever been this turned on.

Dib did the only thing he could under the circumstances and kissed Zim.

Zim made a humming noise against his lips, his hands coming up to curl in Dib’s hair. His mouth tasted chemical-sweet, faintly metallic, and not altogether pleasant. Dib was about to pull back when Zim’s tongue snaked past his teeth and into his mouth, curling over on itself until it was pushed up against Dib’s palate.

Dib jerked back, the sound of his coughing drowned out by Zim’s laughter.

“You—asshole—” Dib gasped, eyes watering. Then Zim kicked his legs out from under him and he landed on his ass on the floor.

Zim planted his bare foot in the center of Dib’s chest—like a violent, disdainful mirror of the way Dib had touched him—and shoved him onto his back.

“What is with you today and kicking me?” Dib asked the ceiling.

“Maybe you’re too filthy for me to touch with my hands,” Zim said, clambering onto Dib’s torso, straddling his stomach. Dib swallowed, hard.

Slowly, Dib propped himself up on his elbows. He lifted up one arm and, still slowly, curled his hand around Zim’s waist. Zim watched him, his eyes shining, ruby red, and unreadable. He stroked his hand up Zim’s flank, feeling the bump of ribs under his fingers.

Zim shivered all over. He trilled, like he had in the bathroom, but louder now.

Dib pushed off the floor with one hand, coming up to sit with his legs stretched out in front of him. Zim was balanced on his thighs, legs spread precariously wide. Dib pressed his thumb into the divot between two of Zim’s ribs, leaning him back, taking a _real_ look at his body, all stretched out and strange.

God, he was so fucking _skinny_. Fleshless. His body was almost featureless apart from the jut of bone underneath skin. 

His hips were wide and between his legs, when Dib finally let his eyes drift down there, was a slit that would have been almost invisible is it weren’t beaded with moisture.

Dib rubbed the thumb of his free hand up the slit. It parted slightly under the pressure, revealing a hint of bright pink. Zim’s hips jerked and he said something, but Dib wasn’t paying attention, raising his hand up to his nose. 

The smell was acrid and too strong this close, like sniffing perfume right out of the bottle. Dib was considering tasting it, his tongue already peeking out of his lips, when he felt clawd fingers sink into his hair. 

Zim gave Dib’s hair a vicious yank. “You want to taste Zim?” he said. He crab walked backwards, dragging Dib with him by the hair until he was on his back with Dib hunched over him. Dib’s shadow stretched over him, dark and long to the back wall. “Taste Zim properly.” He let go of Dib’s hair and reclined, legs spread and blank, insect-eyes watching Dib.

Slowly, in case Zim decided to kick him again, Dib slid back far enough that he could lower himself down to his stomach on the cold floor. He ran his palms along the hairless skin of Zim’s thighs, pushing them open further. He leaned in, running the flat of his tongue lightly up the slit. Cautious, not pushing yet in case Zim had had teeth or stingers or something hidden in there.

When the tip of his tongue wasn’t bitten off, Dib pressed in a little deeper, licking up the full length of the slit. Above him, Zim was making some kind of noise, but Dib was concentrating too hard to pay attention.

Zim tasted like someone mixed the sour powder coating on gummy worms with metal shavings and a couple drops of Windex and Dib had no idea if he found it vile or weirdly pleasant. Either way, he forced his tongue into Zim as deep as it’d go, chasing the taste even as his lips curled back from his teeth and his eyes watered from the fumes.

“Ah!” Zim cried out, his heel banging on Dib’s shoulder. Dib gave the inside of Zim’s thigh a vicious pinch in revenge which made Zim shudder all over.

Dib pulled back and braced his hand on Zim’s stomach, pinning him. He rubbed a finger against Zim’s entrance, eager to explore deeper.

There was a moment of resistance, then his finger sunk right in. Zim threw his head back and howled wordlessly as he pulsed and twitched around Dib’s finger. Dib twisted his wrist experimentally and got kicked in the shoulder again. Hard.

Dib cursed and Zim raised his head to glare at him. _”Do not tease Zim,”_ he hissed.

“_Stop_ fucking kicking me,” Dib said. He pressed another finger roughly into Zim and was ready this time when Zim kicked out. He dodged, grabbing Zim’s ankle, and used the momentum to flip him onto his stomach. “You’re such a fucking asshole,” Dib said, holding Zim down with one hand and fumbing open his pants with slick fingers. “If I’m helping you, the least you could do is not make me look like I got hit by a car.”

“You are not helping Zim out of the goodness of your heart,” Zim said and Dib could hear the snarl even if he couldn’t see it. Zim arched his back, pressing his bony ass back against Dib. “I’ve seen the way you look at me, human. One way or another, you’ve wanted to get inside Zim since you were a worm-child just barely out of the _dirt_.”

Dib couldn’t argue with that. But he could _fuck_ Zim until he couldn’t form coherent sentences. That would have to count as a victory.

He rubbed the head of his cock along Zim’s slit, eyes on the back of Zim’s shoulders for any telltale signs of pain or aggression, but Zim seemed relaxed. Almost docile. As if now that he was finally getting what he wanted, there was no reason to fight.

Dib held his breath and began to push inside. Millimeter by millimeter. Zim was so slick that he glided right in, despite the overwhelming tightness. 

Zim shuddered all over, keening.

“Are you okay?” Dib gasped. His vision kept going in and out of focus.

“Zim is fine!” Zim snapped then gave a full-body twitch when Dib rolled his hips experimentally. “Zim has never been better,” he said, voice about half an octave higher than usual. Dib grinned to himself even as Zim’s muscles rippled around him, making his eyes cross.

Zim felt so strange, like he had some kind of filia or little nubs lining his insides. Dib was quickly losing a grasp on coherent thought, but he hoped fervently that he would get a chance some day to prop Zim up on the edge of a table and take a thorough _look_. Everything had happened too fast this time, but next time—wait, next time?—all he’d need was a penlight and a speculum and for Zim to hold still long enough to—

Something _inside Zim_ curled around Dib’s cock like long, prehensile tongue and Dib’s orgasm was punched out of him along with all the air from his lungs. He fell forward, almost smacking his face into Zim’s PAK, but caught himself at the last moment.

He just knelt there for a long moment, too woozy to do anything but let whatever that thing was milk the aftershocks out of him until oversensitivity finally made him recoil.

Bracing one hand on Zim’s hip, he pulled out. About nine inches of tentacle came out with him. Still sullenly curled around his cock like it didn’t want to let him go.

“Um,” he said, still too high on endorphins to be alarmed. He gave the bright pink thing a poke and it rippled all along its length, making both Dib and Zim twitch. “Zim, a little help?”

Zim said something Dib couldn’t understand, but which sounded rude, so that probably meant Dib was on his own when it came to untangling his genitals from Zim’s genitals.

He gave the tentacle another poke, then, when that didn’t work, he grasped it gently by the tip and began to manually unwind it from his softening cock. Once he’d freed himself, it curled instead around his fingers and the palm of his hand, pulsing lightly. 

Now that Dib was no longer half out of his mind with horniness, he had enough room emotionally to be _fascinated_. The tentacle was slick and warm—much warmer than Zim’s skin. It writhed lazily in Dib’s hands, and despite its softness, he could feel its muscular strength. It reminded him a bit of touching an earthworm, but bigger, stranger, and alarmingly hot.

In a burst of intuition, Dib curled his fingers around the base of the tentacle, where it disappeared into Zim’s body, and stroked it all up its length. Zim jolted, so Dib did it again, firmer this time. Zim whined, the sound pitching up and up as Dib sped up until he was stroking the tentacle hand over hand like he was trying to haul rope. Then Zim yelled, and Dib found himself with a slimy handful of tiny, translucent eggs. Each the size of a marble.

The tentacle slid from his fingers back into Zim’s body, leaving him with a mess spilling over his fingers onto the floor.

After a moment, Zim wobbled upright, spinning on his knees to see Dib with his double handful of Irken eggs. He reached out and plucked one up with his claws, inspecting it. 

“Unfertilized,” he said with satisfaction and dropped the eggs back into the gooey pile. He collapsed back onto the floor in a sprawl. He closed his eyes and was silent.

“Uh, what am I supposed to do with these?” Dib eventually asked. 

Zim waved a hand in the air lazily. “Just leave them on the floor or something. I’ll have GIR dispose of them later.”

“Can I have some?”

“No.”

“Whatever.” Dib let the eggs slide through his fingers on to the floor. Save for five, which he pocketed after making sure Zim wasn’t looking. Shakily, he got to his feet, straightening his clothes.

He was about to leave when he looked down at Zim, still spreadeagled on the floor. He looked so very small and so very alien and it was beginning to dawn on Dib that he had had sex with him. Like, real, actual home base sex. With Zim.

“Was…” Dib trailed off. He had the feeling he’d be laughed at if he asked if Zim had enjoyed it. “Was that what you needed?”

“It was satisfactory,” Zim said, one arm was flung over his eyes, his skin was slick with sweat and both their juices. He turned his head towards Dib, one eye cracking open. “Now get out of my house.”

**Author's Note:**

> This fic is dedicated to everyone on the 18+ discord, who are a constant inspiration to me. Y'all the cosmic wind beneath my spittle runner's wings.
> 
> Come bother me on [tumblr](http://www.largishcat.tumblr.com).


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